1. Technical Field
The present invention relates to a vehicular lamp and more particularly to a vehicular lamp that is manufactured at low cost.
2. Description of the Related Art
Some of the recent vehicular lamps are equipped with circuitries.
For installing a circuitry in a vehicular lamp, the circuitry is formed on a hard substrate or an FPC (Flexible Printed Circuit), and this substrate or an FPC that has the circuitry mounted is installed in a vehicular lamp.
However, building a circuitry on a hard substrate inevitably tends to restrict the shape of the vehicular lamp to which the circuitry is applied. In other words, a hard substrate only allows flat placement of electronic components, which is a problem. Thus, when a light-emitting diode, for example, is used as a light source in place of an incandescent bulb, the light-emitting bulb can only be disposed flatly; and as a result, in vehicular lamps that use hard substrates, the light-emitting diodes are installed only flatly.
On the contrary, an FPC has flexibility and thus can be bent or curved at any desired positions, thus allowing a three-dimensional arrangement of light-emitting diodes. However, the FPC becomes exclusive to each vehicular lamp type, and the manufacture of which requires many complicated processes; as a result, since vehicular lamps generally come in a wide variety of types and thus involve limitations in the number of production, vehicle lamps that use the FPC have problems in view of the manufacturing costs. Moreover, since the FPC wiring conductor uses extremely thin copper foil or the like, there is almost no expectation for a heat dissipation effect via the wiring conductor.
Japanese Patent Application Laid-Open (Kokai) No. 2000-260206 proposes a vehicular lamp in which the luminescent element module with light-emitting diodes mounted on parallel bus bars is disposed on the back surface of the lamp body.
Using the bus bar as a base for mounting the light-emitting diode considerably reduces the manufacturing costs compared with the use of FPC.
In the vehicular lamp of the Japanese Patent Application Laid-Open (Kokai) No. 2000-260206, the position of the light-emitting diode is determined in accordance with the lamp body shape by way of mounting the light-emitting diodes on parallel bus bars and then bending the bus bars. Accordingly, there is a freedom in the lamp body shape design, and a heat dissipation effect via the bus bars can be expected.
However, the bus bar is formed from a thick metal plate that has high rigidity, which makes it difficult to position the bus bar along the back surface of the lamp body which also has high rigidity and a complicated three-dimensional shape. This consequently limits the shape of the lamp body to which the bus bar is applied.
Furthermore, each bus bar is an independent element, and therefore, a plurality of bus bars must be individually installed in the lamp body. This in turn makes the work for installing the luminescent element module and circuit module on the body more complicated. More labor is required for larger lamp bodies, and an increase in the manufacturing cost is unavoidable.
It is also difficult to configure complicated circuitries.